Unfolding long-term Late Pleistocene–Holocene disturbances of forest communities in the southwestern Amazonian lowlands
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2018
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Ecosphere
Resumo
Linking the distribution of plant species to geology has generally been biased by the oversimplification
of landscape evolution and the lack of understanding of complex geological processes. The
Amazonian lowlands have forests in different successional stages, and a growing perception is that such
heterogeneity results from long-term environmental changes. This hypothesis is investigated by designing
an analytical model based on past and present-day vegetation and successions of the plant communities,
combined with an advanced understanding of geological history. An area of southwestern Amazonia was
selected for floristic inventories, and we interpreted the paleovegetation based on C/N and d13C analyses
of sedimentary organic matter. These data were examined in the context of the geological evolution on the
basis of new sedimentological and chronological data. The topographically high Late Pleistocene deposits
had continuous and highly diversified late-successional terra firme forests as well as local fluvial paleolandforms
of younger ages with less diversified campinarana forests. Late Pleistocene–Holocene terrains
in intermediate elevations had terra firme forests, but shorter trees with lower basal areas and ecotonal forests
appeared near the confines of the forest–savanna, while Holocene deposits recorded only seasonally
flooded varzea forests. Several deposits of Late Pleistocene and Late Pleistocene–Holocene age recorded an
expansion of C4 terrestrial plants before the establishment of the forest from ~20,000 cal yr BP to 7578 cal
yr BP, which is not related to past arid episodes. We recorded forests with onsets at 6130–3533 cal yr BP,
3402–2800 cal yr BP, and 1624–964 cal yr BP to terra firme, varzea, and ecotonal forests, respectively. However,
not all forests have reached maturity stages due to their location on terrains with a diverse history of
terrace downcutting and deposition, which had a direct impact on local hydrology with the interaction of
topographic gradients. The hydrology of the study area was also controlled by the distance from the main
river valley. Capturing long-term disturbances over this region of still pristine forests may help elucidate
the potential mechanisms that also determine trends in tree growth and forest diversity in other Neotropical
regions.
Como referenciar
ROSSETTI, DILCE R.; GRIBEL, ROGERIO; TOLEDO, PETER M.; TATUMI, SONIA H.; YEE, MARCIO; TUDELA, DIEGO R.G.; MUNITA, CASIMIRO S.; COELHO, LUIZ de S. Unfolding long-term Late Pleistocene–Holocene disturbances of forest communities in the southwestern Amazonian lowlands. Ecosphere, v. 9, n. 10, p. e02457-1 - e02457-32, 2018. DOI: 10.1002/ecs2.2457. Disponível em: http://repositorio.ipen.br/handle/123456789/29798. Acesso em: 19 Apr 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.